Method and apparatus for solid transfer



Patented Jan. 20, 1953 METHOD AND APPARATUS FOR SOLID TRANSFER Robert C. Wilson, Jr., Woodbury, N. J., assignor to Socony-Vacuum Oil Company, Incorporated,

a. corporation of New York 7 Application March 15, 1945, Serial No. 582,95

10 Claims.

This invention relates to method and apparatus for handling solid material in gas-solid or vaporsolid contact processes. Such processes may involve gas-solid heat exchange, gas adsorption, gasiform reactions in presence of catalysts, gassolid reactions, solid regeneration or solid treatment. Typical processes are those of the high temperature treatment of oil bearing shales for recovery of hydrocarbons and the catalytic cracking of petroleum gas oil for the production of gasoline. For example, in the treatment of oil bearing shales, it is well known that hydrocarbons may be vaporized and recovered therefrom by the heating of such shales to temperatures usually in excess of about 1000 F. Such processes may be operated at substantially atmospheric pressures or at pressures thereabove and generally involve vapors which are condensible at ordinary atmospheric conditions.

A convenient method for solid introduction to gas-solid contact zones is by means of a substantially compact elongated column of downwardly gravitating solid particles. This invention is specifically directed to certain improvements in this method of solid feed introduction. When such feed legs are used for solid introduction, small quantities of gasiform material from the reaction zone tend to escape upwardly through the solid feed leg. In order to prevent such reactant or contact gas escape, an inert seal vapor, such as steam, may be introduced into the lower section of the feed leg. Some of this steam makes its way upwardly through the feed leg and if the solid feed particles are at a relatively low temperature, such as atmospheric temperature, the steam will be condensed on the solid particles. This condensation of vapor may eventually cause clogging or bridging of the solid flow in the feed leg resulting in partial or complete stoppage of solid flow to the contacting zone.

It is a major object of this invention to provide a method and apparatus for introduction of a relatively low temperature supply of solid particles to a gas-solid or vapor-solid contacting zone.

A specific object of this invention is the provision of a method and apparatus for gravity feeding of particle form solid particles to a gas-solid contacting zone while preventing substantial escape of contacting gases and while preventing substantial vapor condensation on the feeding solid particles.

Another specific object of this invention is the provision of a method and apparatus for intro- I 2 ducing oil-bearing shale particles into 'ahigh temperature shale treating zone.

These and other objects of this invention will become apparent from the following description of the invention.

Before proceeding with this description, certain terms used hereinbefore and hereinafter in describing the invention and in the claiming thereof will be defined. The terms gas or gasiform material or gasiform fiuidunless otherwise specifically modified to the contrary are intended to broadly cover material in the gaseous phase at the conditions involved irrespective of the normal phase of the material at normal atmospheric conditions. The terms vapor or vaporous material are intended to mean material in the gaseous phase which would exist in the liquid phase under the temperature and pressure conditions of the feed solid at the entrance of the solid feed conduit.

The terms normally gaseous fluid or .normally gaseous material are intended to mean material in the gaseous phase which normally exists in the gaseous phase under the temperature and pressure conditions of the feed solid at the entrance to the solid feed conduit.

The invention may be more readily understood by reference to the attached drawings of which Figure 1 is an elevational view, partially in section, of a preferred form of this invention and Figure 2 is a similar view of a modified form of the invention. Both of these drawings are highly diagrammatic in form.

Turning now toFigure 1, we find a closed conitactingvessel l0, which may take anysuitable form adapted for the particular gas solid contact operation involved. A gasiform material inlet H is connected into the lower section of the vessel and a gasiform material outlet I2 at the upper section thereof. Gas distributor members (not shown) may be provided in association with inlet conduit l l and these may take any of a number of forms well known to those skilled in the art. A solid material feed conduit l6 extends a considerable distance above the top I 5 of vessel l0 and on its lower end extends through top l5 and a short distance therebelow so as to provide gas disengaging space 30. The conduit It should be of suificient length to insure fiow of solid material therethrough and into the contacting vessel It against whatever pressure may exist therein. A pipe [8 with valve l9 thereon connects into'the lower section of conduit l6, and a perforated, rounded plate 20 is provided over the open end-of pipe l8 to prevent solid fiow thereinto while permitting gas fiow therethrough, A number of louvered openings 2| are provided at an intermediate level on conduit it; these openings are so constructed as to permit withdrawal of gasiform material without substantial loss of solid particles. A manifold box 22 is fastened to the conduitl6 around the louvered section and a vapor outlet pipe 23 is connected into this manifold box. A drain pipe 24 may be provided on the bottom of the manifold box for periodical removal of any small quantity of entrained solid particles. A pipe 25 for gas inlet is connected into the conduit l6 at a level substantially above that of the louvered section and a perforated metal plate 25 is provided at its inlet to prevent solidflow into therefrom through conduit 13 and valve I l. The" contacting or reactant gases are heated to the desired temperature in an outside apparatus (not shown)- which maybe of conventional construction and then admitted through conduit H and passed upwardly through the solid material in vessel It]. The gaseous products are then withdrawn through conduit l2 through which they pass to a suitable recovery system (not shown). If desired, gasiform materia1 may be introduced through conduit I I 2' and withdrawn through conduit H to efiect' concurrent flow of solid and gaseous material through the vessel it. The temperature and pressure conditions within the vessel will vary depending upon the operation involved. Generally elevated temperatures substantially above atmospheric temperature and ressures from about atmospheric to about 50 pounds per square inch may be maintained. A bed of particle form solid feed material is maintained in hopper l7 and feed therefrom downwardly through the conduit 16; The size of such solid particles may vary depending upon the operation involved but will be generally of sizes within the range of about 0.01 to 1 inch solid particle diameter. Thus, for example, the average particle diameter may be of the order of 0.02 to 0.2 inch for hydrocarbon cracking catalysts, while for oil bearing shales the particle size may be generally larger.

An inert vapor, such as steam, is introduced into the feed conduit through pipe 18 and passes inv part downwardly through conduit l6 and out with contact gases through conduit l2 and in part upwardly through the compact stream of solid. particles in conduit IE to be withdrawn through louvered openings 2! and outlet pipe 23. An. inert normally gaseousfluid, such as flue gas, is introduced through pipe 25 into conduit 56 and. this stream divides, part passing upwardly and out through the hopper H and part passing downwardly to be withdrawn through pipe 23 along with the seal vapor. The inert gas so introduced is heated in a suitable external apparatus (not shown) such as a conventional line burner and introduced into conduit it at such a temperature and rate as to heat the moving solid particles in that section of the conduit it above the louvered outlets 2 I, so that said solid particles, upon reaching the louvered section 21, are at a temperature above the condensation temperature of the seal vapor employed. The inert gas passing downwardly through the solid material from inlet pipe 25 further serves to substantially prevent flow of seal vapor upwardly into that section of the column above the louvered outlets 2! -where the solid temperature is below the condensation temperature of the seal vapor. Thus the condensation of seal vapor upon the solid feed particles is substantially avoided and the dimculties arising from such condensation are eliminated.

As hereinabove stated, the height of the conduit It should be sufiicient toprovide a head of solid particle column therein suiiicient to overcome the gaseous pressure within the vessel It]. The required height will obviously vary depending on the operation involved and especially upon the density and physical properties of the solid particles involved. For example, in the case of claytype granular material of about 40 pounds per cubic foot apparent unpacked density a height of 'aboutfour feet per pound of pressure to be overcomein vessel. it) has been found satisfactory. The required height will be greater for less dense materials and less for more dense materials. If the pressure at the seal vapor outlet conduit 23 is to be substantially atmospheric, then the height of conduit it up to that level should besufiicient to permit a head of solid material between that level and the vessel It somewhat greater than that required to overcome the differential in pressure between that in vessel I0 and atmospheric pressure. In order to permit maximum utilization of available column" height, especially in-those operations wherein the pressure in vessel it is substantial, it is desirable to control the gaseous pressure at the level of conduit 23 above atmospheric and preferably near that pressure which would exist at the level of conduit 23 if it were absent and the seal vapor were forced to flow upwardly through the entire conduit it. Thus, for example, assuming a gaseous pressure in the vessel IQ of 5-pounds per square inch gauge and a solid clay-type material of 40 pounds per cubic foot density, supplied to hopper I? at atmospheric pressure, in the absenceof vapor'withdrawal at louvers 2! the conduit l6 should be about 29 feet high to overcome the pressure within vessel [5; and in order to allow for fluctuations in pressure, the conduit should be about 25 to 30 feet in height. Now assuming the seal vapor inlet IB to be about 1 foot above the lower end of conduit I 6 and the seal vapor outlet 23 to be about 4 feet further up the conduit It, the gaseous pressure at the level of outlet 23 should be controlled near about 4 pounds per square inch gauge or slightly thereabove. Thus a diaphragm valve 27 provided on outlet 23 would be regulated to control the vapor and normally gaseous fluid flow through conduit 23 such that the pressure within conduit l5 at this level is maintained within a narrow range. of pressures, say 4% .to fl i-f/infi, which are about three-quarters of a pound per square inch below the pressure in vessel I0. The diaphragm valve 21 is so regulated by means of the differential pressure control instrument 28. Similarly another diaphragm valve 29 is provided on inert gas inlet pipe 25 to control through differential pressure controller 3| the pressure within conduit H5 at the level of pipe 25 slightly above that in the conduit H5 at the seal vapor withdrawal level. The purpose of this control is to insure downward passage through conduit iii of at least part of the normally gaseous heating fluid introduced through pipe 25. Inasmuch as the length of conduit between the levels of inlet pipe 25 and outlet pipe 23 is lost for purposes of overcoming pressure in the vessel Iii, it is desirable to limit the length of the column between these levels as low as is consistent with provision of the proper heating of the solid material by the normally gaseous fluid. Since the heat transfer rates for direct contact of gases with solids are very high, generally the length of column between the levels of inlet pipe and outlet pipe 23 need be no greater than about one to two feet. It should be understood, however, that while where solid feed material is introduced to contact zones operating under substantial pressures the use of diiferential pressure control mechanisms, such as outlined hereinabove, is exemplary of the preferred form of this invention, nevertheless the use of such mechanisms is generally unnecessary for relatively low pressure operations and may also be omitted for higher pressure operations, where the provisionof additional feed conduit height is unobjectionable from a practical standpoint. The invention, therefore, is not to be construed as limited in all applications to the use of such pressure control mechanisms nor, when used,-to the particular example given hereinabove.

Turning now to Figure 2, we find another form of the invention modified mainly with respect to the method for heating the solid particles in the upper section of the feed conduit. Lik members in Figures 1 and 2 bear like numerals. In Figure 2, only the upper section of the contacting vessel I0 is shown and it will be noted that the upper section of this vessel is somewhat modified by provision of partition 32 and dependent solid material distributor pipes 33 and flanged top 34. The partition 32 and flanged top 34 provide a solid material distirbution space 35 which may also serve as a seal section by provision of a seal vapor inlet pipe 36 having valve 31 thereon on the vessel top 34. Seal vapor may, if desired, be introduced through conduit 36, in which case part of the seal vapor enters the lower end of the solid material feed conduit l6 and passes upwardly through the solid material therein, thereby eliminating the necessity for seal vapor introduction directly into the conduit 1 6- at some level thereabove. On the other hand, if desired, seal vapor may be introduced directly into the conduit 16 through inlet conduit 38, manifold box 39 and louvered openings 40 provided on the lower section of conduit IS. The seal vapor is withdrawn through louvered openings 4! and 42 which are similar to those shown in Figure 1 except that a double row of such openings is provided to further limit solid particle entrainment. A jacket 43 having heating fluid inlet 44 and outlet 45 thereon is provided along a section of conduit 16 above the seal gas withdrawal level to provide for heating of the solid material by indirect heat transfer with a heat exchange fluid. Any suitable heat exchange fluid, such as superheated steam, molten alloys or molten salts may be circulated through the jacket 43 and through a suitable external heating and circulating system which may be of conventional design and is, consequently, not shown. Other suitable indirect heat transfer arrangements may be provided instead of the jacket arrangement shown, such as small tubes within the upper section of conduit I6. When the solid material is so heated by indirect heat transfer, it is desirable to maintain a slightly reduced pressure on the seal vapor outlet conduit 23 so as to prevent flow of seal vapor into the cooler solid material thereabove. This may be effected by the use of a jet condenser, as shown, or by other suitable and conventional vacuum creating apparatus. Alternately, if desired, a small amount of normally gaseous fluid may be injected into the column a short distance above the seal vapor outlet level to prevent the rise of seal vapor into the solid material thereabove, while still employing indirect heat transfer means for heating the solid material to a temperature above the condensation temperature of the seal vapor. In such case the use of the jet condenser is unnecessary.

The hereinabove described invention has been found particularly useful in a process for recovery of hydrocarbons at elevated temperatures from oil-bearing shales. In this process superheated steam was introduced into the lower section of the solid feed conduit as a seal vapor to prevent the escape of hydrocarbons through the feed conduit. Shale particles ranging from 1 to 0.125 inch average diameter were introduced into the upper end of the feed conduit and utilizing the method and apparatus hereinabove described, uninterrupted continuous feed of shale to the treating zone was provided without the clogging and interruption of feed flow which ordinarily results due to steam condensation 0n the low tempera ture shale in the feed conduit.

It should be understood that the details of apparatus construction and operating conditions and the systems shown to which this invention may be applied are intended merely as exemplary and are in no way to be construed as limiting the scope of this invention except as it may be limited by the following claims.

I claim:

1. In a system comprising an elongated feed conduit extending upwardly from a confined contacting vessel for gravity feed of particle-form solid feed material into said vessel the improvement comprising, an inlet pipe connecting into said elongated feed conduit near its lower end for seal vapor introduction thereinto, a gas outlet communicating with the interior of said feed conduit at an intermediate level along its length, a gas inlet pipe connecting into said feed conduit a substantial distance above said outlet, a flow control valve on said last named pipe, a differential pressure control instrument connected operatively with said valve and communicated with said feed pipe at the levels of said outlet and of said last named inlet pipe, whereby said valve may be controlled in response to change in pressure differential between said outlet and said last named inlet pipe.

2. In a process wherein a particle form solid material of size within the range about 0.01-1 inch average diameter is continuously passed through a confined contacting zone wherein it is contacted at elevated temperatures and superatmospheric pressures with a gaseous fluid which should be maintained confined from the atmosphere, the method of introducing the solid feed material to said contacting zone from a supply zone maintained at a lower pressure than exists in said contacting zone which comprises, continuously flowing said particle-form solid material from said supply zone by gravity into said confined contacting zone as a substantially compact, confined, continuous, moving feed stream of particles extending upwardly from said contacting zone to said supply zone through a vertical distance sufficient to insure gravity feed into said contacting zone against said superatmospheric pressure existing therein, withdrawing the contacted gaseous fluid from said contacting zone without passage through any portion of said feed stream while maintaining said superatmospheric pressure in. said contacting zone, introducing a seal vapor which is different fromsaid contacted-gaseous fluid into the lowersection-oi stream, withdrawing gaseous material from said feed stream at an intermediate'level substantially above the lower end of said stream, controlling the gaseous pressure in said feed stream at said level of fluid withdrawal below the pressure in that portion of said contacting zone into which said stream flows, introducing a substantially inert normally gaseous heated fluid into said stream at a level above said level of fluid withdrawal, at a sufficient temperature and rate to heat said solid material from a temperature below the condensation temperature of said seal vapor to atemperature above the condensation temperature thereof, .and'controlling the gaseous pressure at said level of said normally gaseous heated .fluid introduction into said stream above the pressure at said level of fluid withdrawal from said stream but below the pressure in said contacting zone,

3. The method of continuously conducting reactions above atmospheric pressure and at elevated temperatures involving gaseous hydrocarbon reactants in the presence of a IIlOViIlg particle form solid contact mass material of size Within the range about 0.01 to 1 inch average diameter which comprises: passing said solid material as a substantially compact column of solid particles moving continuously downwardly through a reaction zone while contacting it with hydrocarbon reactant gases at superatmospheric pressure and at elevated temperatures suitable for effecting the reaction, withdrawing particle form solid material from the lower end of said zone, continuously flowing said solid material by gravity from a supply zone maintained at a pressure substantially below the: pressure in said reaction zone into said reaction'zone as a substantially continuous, cornpact, confined moving feed stream of said solid material extending upwardly without interruption from said reaction zone to said supply zone through a suflicient height to insure solid material gravitation into said reaction zone against the superatmospheric pressure existing therein, withdrawing said hydrocarbon reactant gases directly from said reaction zone without passage through any portion of said feed stream while maintaining said superatmospheric pressure in said reaction zone, introducing an inert seal vapor into the lower section of said feed stream to prevent escape of reactant vapors therethrough, withdrawing seal vapors from said feed stream at an intermediate level a substantial distance above the lower end of said stream, whereby the pressure in said stream at said intermediate level is maintained below that in said stream immediately thereabove and therebelow, thereby preventing upward flow of vapors pass said intermediate level to the upper section of said stream, introducing a normally gaseous inert fluid into said feed stream at a level substantially above said level of seal vapor withdrawal at a temperature and rate adjusted to heat said solid material from a temperature below the condensation of said seal vapor to a temperature above the condensation temperature thereof, and maintaining the gaseous pressure at said level of normally gaseous fluid introduction above that at said level of seal vapor withdrawal but below that at the level of seal vapor introduction.

4. In a process for recovery of hydrocarbons from oil shale particles of size within the range 7 about 0014 inch diameter by continuous treat- 8 ment in a. confined treating zone atsuperatmospheric pressure and high temperatures suflicient to efiect release of the hydrocarbons in gaseous form from said shale particles, the method of introducing the shale to said treating zone from a supply zone maintained at a lower pressure than the treating zone which comprises, continuously flowing said shale by gravity from said supply zone into said treating zone as a substantially compact, confined, continuous moving stream of particles extending upwardly without interruption from said treating zone through a suificient height to said supply zone to insure gravity feed into said confined treating zone against said superatmospheric pressure existing therein, withdrawing recovered vapors from said treating zone without passage through any portion of said compact stream while maintaining said superatmospheric pressure in said zone, introducing aninert seal fluid in gaseous phase into the lower section of said feed stream to substantially prevent entry of recovered hydrocarbon vapors into said feed stream, introducing a substantially inert normally gaseous fluid into said feed stream at a level in the upper section thereof so as to maintain gaseous pressure at said level of introduction which is below that in the upper portion of said treating zone but above that in the portion of said feed stream immediately below said level of introduction, said inert fluid being introduced at a temperature and rate controlled to effect heating of said shale from a temperature below the condensation temperature of said first named seal fluid to a temperature above the condensation temperature thereof, withdrawing gaseous material from said feed stream at an intermediate level between the levels of said seal fluid and said normally gaseous fluid introduction so as to maintain the pressure in said feed stream at said level of withdrawal .below that at said levels of said seal fluid and said normally gaseous fluid introduction.

5. Apparatus for conducting gasiphase reactions at pressures above atmospheric in the presence of a moving particle-form olid contact mass material which comprises: a reaction Vessel adapted for passage therethrough of a particleform solid material as a substantially compact column of downwardly moving solid particles, a gas inlet to said vessel and a gas outlet therefrom spaced apart from said inlet, an elongated vertical feed conduit vfor solids extending upwardly from the top of said vessel and means to supply solids tothe upper end of said feed conduit, a gas inlet pipe connected to said feed conduitnear its lower end so as to be in communication with the interior of said feed pipe, a plurality oflouvred openings around said feed conduit .at a level spaced a substantial distance above said gas inlet pipe, said louvred openings being adapted to permit passage of gas therethrough while preventing gravity flow of solid particles therethrough, a gas outlet manifold box connected around said column at the level of said louvred openings, a gas outlet pipe connecting into said manifold box, an automatic flow control valve on said pipe and an actuating instrument therefore adapted to automatically control the pressure in said conduit at the level of said louvred openings within a fixed range which is above atmospheric and below the pressure Within said reaction vessel, a gas inlet pipe connected into said feed conduit at a level intermediate its upper end and the level or said luuvcLd openings, means to supply heated gas to said last named inlet pipe, and an automatic flow control valve on said last named inlet pipe and an actuating instrument associated with said valve adapted to control the pressure within said feed conduit at the. level of said last named inlet a fixed amount above the pressure at the level of rial to said treating zone from a supply zone maintained at a lower pressure than the treating zone which comprises: continuously flowing said particle form solid feed material by gravity from said supply zone into said confined treating zone as a substantially compact, confined, continuous moving feed stream of particles extending upwardly without interruption from said treating zone through a suflicient height to insure gravity feedinto said confined treating zone against said superatmospheric pressureexisting therein, withdrawing recovered vapors from said treating zone without-passage through any portion of said compact stream while maintaining said sup'eratmos pheric pressure in said zone, introducing a seal vapor which is different from said recovered vapors into the lower section of said feed stream to/substantially prevent entry of any of said recovered vapors into said feed stream Withdrawing gaseous material from said feed stream at an intermediate level substantially above the lower end of said stream, controlling the gaseous pressure in said stream at said level of fluid withdrawal below the pressure in that portion of said treating zone into which said stream flows, introducing a substantially inert normally gaseous heated fluid into said stream at a level above said level of fluid withdrawal, at a suflicient temperature and rate to heat said solid material from a temperature below the condensation temperature of said seal vapor to a temperature above the condensation temperature thereof, and controlling the gaseous pressure at said level of said normally gaseous heated fluid introduction into said stream above the pressure at said level of fluid withdrawal from said stream but below the pressure in said treating zone.

7. Apparatus for conducting gas-solid contact operations at pressures above atmospheric in the presence of moving particle-form contact material which comprises: an upright reaction vessel closed on its ends and having an outlet conduit for solids withdrawal connected into its lower end and having a gas inlet and a gas outlet, a vertical solid material feed conduit extending upwardly from the upper section of said vessel to a supply hopper spaced a substantial vertical distance above said vessel, a gas inlet pipe connected into said conduit near but above its lower end, a valve associated with said inlet, a gas outlet communicating with the interior of said conduit at an intermediate level along its length, an outlet flow control valve associated with said outlet, an automatic differential pressure controller associated with said outlet flow control valve operatively connected to control the pressure in said feed conduit at the level of said outlet within a fixed range which is above atmospheric and below the pressure within said reaction vessel, a gas inlet near its upper end, an inlet flow control valve associated with saidinlet and an automatic ,dif'- ferential pressure controller associated with said communicating with the; inside of said conduit inlet flow control valve operatively connected to control the pressure in said feed conduit at the level of said last named inlet a flxedamount above the pressure in said feed conduit at the level of said outlet. 1

8. A continuous method for treating particleform solid materials of size within the range about 0.0l'1 inch average diameter containing constituents recoverable as vapors by continuous treatment at superatmospheric pressures and elevated temperatures suitable for effecting release of said recoverable material from the solid material in a confined treating zone which comprises, continuously flowing said solid material existing initially at a temperature below that at which said recoverable constituent are vaporized downwardly into said treating zone as a substantially compact confined continuous feed stream of moving particles extending upwardly from said, treating zone through a sufiicient vertical dis-- rial through said treating zone while subjecting it at superatmospheric pressure to elevated tem peratures to drive ofi said recoverable constit'uents as vapors, withdrawing said vapors directly from said treating zone without passing them through any portion ofsaid compact solid mate'-w rial feed stream while maintaining said superat-j mospheric pressure in said treating zone, introducing a seal vapor which is difierent from said recoverable vapors and which is substantially inert into the lower section of said feed stream to substantially prevent the entry of any of said recovered vapors into said feed stream, heating said solid material in said feed stream along an upper section of said feed stream from a temperature below the condensation temperature of said inert vapor to a temperature above said condensation temperature, withdrawing said seal vapor from said feed stream at an intermediate level between the level of said seal vapor introduction and said upper section of heating and maintaining the pressure at said intermediate level below the pressure at said level of seal vapor introduction and below the pressure along at least a portion of the section of said stream which is undergoing heating whereby upward vapor now from said intermediate level to the portion of the feed stream thereabove is prevented.

9. A continuous method for continuously subjecting particle-form solid materials of size within the range about 0.01-1 inch average diameter to contacting in a confined contacting zone at superatmospneric pressure and elevated temperatures substantially above the initial temperature of the solid material with a gaseous material which would undergo reaction with air if permitted to escape to the atmosphere at said elevated temperatures, which method comprises, continuously flowing said solid material existing initially at a low temperature level relative to that in said confined zone downwardly by gravity from a supply zone maintained at a pressure substantially below the pressure in said contacting zone into said contacting zone as a substantially compact, confined, continuous, moving feed stream of particles extending upwardly without obstruction from said contacting zo'n'ethrough a suificien't vertical distance to said supply zone to insure feed into said contacting zone by gravity alone against said 'supera'tmospheric pressure existing therein, passing the solid material through said contacting zone while subjecting it to contact with gaseous material at superatmospheric pressure and an elevated temperature substantially above that of the solid material in said'supply zone, withdrawing the gaseous material after contact with said solid material directly from said contacting zone without passing it through any portion of said feed stream while maintaining said superatmospheric pressure in said contacting zone, introducing a seal vapor which is difie'r'ent from said gaseous material and which is substantially inert into the lower section of said feed stream to substantially prevent entry of any of said gaseous. material from the contacting zone into said feed stream, heating said solid material in said feed stream along an upper section of said stream from a temperaturebelow the condensation temperature of said seal vapor to a temperature above said condensation temperature, withdrawing said seal vapor from said feed stream at an intermediate level between the level of said seal vapor introduction and said upper section of heating and maintaining the pressure at said intermediate level below the pressure at said level of seal vapor introduction and below the pressure along at least a portion of the section of said stream which is undergoing heating, whereby upward vapor new from said intermediate level to the portion of the feed stream thereabove is prevented.

10'. The method of claim 9 characterized by the fact that said'solid material is heated in the upper section of said feed stream from a temperature below the condensation temperature of said seal vapor to a temperature above said condensation temperature by passing a heating fluid in indirect heat exchange relationship with the solid material along said upper section of said feed stream. 7

ROBERT 0. WILSON, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Oil and Gas Journal, vol. 41, pages 96, 99; 100, 102 and 104 (1942).

Ser. No. 434,440, Woog (A. P. 0.), published June 1, 1943. 

1. IN A SYSTEM COMPRISING AN ELONGATED FEED CONDUTI EXTENDING UPWARDLY FROM A CONFINED CONTACTING VESSEL FOR GRAVITY FEED OF PARTICLE-FORM SOLID FEED MATERIAL INTO SAID VESSEL THE IMPROVEMENT COMPRISING, AN INLET PIPE CONNECTING INTO SAID ELONGATED FEED CONDUIT NEAR ITS LOWER END FOR SEAL VAPOR INTRODUCTION THEREINTO, A GAS OUTLET COMMUNICATING WITH THE INTERIOR OF SAID FEED CONDUIT AT AN INTERMEDIATE LEVEL ALONG ITS LENGTH, A GAS INLET PIPE CONNECTING INTO SAID FEED CONDUIT A SUBSTANTIAL DISTANCE ABOVE SAID OUTLET, A FLOW CONTROL VALVE ON SAID LAST NAMED PIPE, A DIFFERENTIAL PRESSURE CONTROL INSTRUMENT CONNECTED OPERATIVELY WITH SAID VALVE AND COMMUNICATED WITH SAID FEED PIPE AT THE LEVELS OF SAID OUTLET AND OF SAID LAST NAMED INLET PIPE, WHEREBY SAID VALVE MAY BE CONTROLLED IN RESPONSE TO CHANGE IN PRESSURE DIFFERENTIAL BETWEEN SAID OUTLET AND SAID LAST NAMED INLET PIPE. 